Long before engaging in a shooting war, Russia and Ukraine were in an energy war. Bitter disputes over natural gas supply predate the current battle by almost two decades.

Russia’s escalating invasions have since drawn tightening sanctions on its energy sector, including a decisive rupture with Western Europe in 2022. And over the past two years, Ukraine’s power grid and oil infrastructure have been prime targets for Russian barrages.

Now Ukraine is hitting back at the industry that bankrolls Russia’s war machine. A recent spate of attacks, mostly on Russian oil refineries, has the potential to roil not just Moscow’s war effort but also global energy markets and even U.S. politics.